This invention relates to uses of povidone-iodine, particularly uses of povidone-iodine as ophthalmic preparations.
U.S. Pat. No. 2,706,701 issued to Beller teaches a polyvinylpyrrolidone-iodine (povidone-iodine) composition that has proven to be an effective antimicrobial topical preparation. Topical uses include sterilization of skin, either on a proposed incision site, or the hands of the surgical team.
The primary purpose of povidone-iodine is its use as an antiseptic preparation. U.S. Pat. No. 4,113,857 issued to Shetty teaches various uses of povidone-iodine. These uses include mouthwashes, handwashes, ointments, shampoos, douches, scrubs, and gargles.
In the United States, newborn babies are universally given topical prophylactic antimicrobial ophthalmic treatment. This procedure is used to prevent various types of infectious conjunctivitis, especially those caused by the gonococcus (Neisseria gonnorrhoeae) and chlamydia (Chlamydia trachomatis) microorganisms.
The conventional topical drug for neonatal ophthalmic antimicrobial prophylaxis has been silver nitrate. However, silver nitrate is somewhat irritating and can cause chemical conjunctivitis. This chemically-induced cojunctivitis can be differentiated from bacterial conjunctivitis only by culturing the conjunctiva of the affected individual to exclude the presence of bacteria. Furthermore, although silver nitrate has excellent activity against the gonococcus, it has poor activity against the chlamydia microorganism.
In response to the problem of chemical conjunctivitis, and the fact that silver nitrate is ineffective against Chlamydia trachomatis--now the most common cause of neonatal conjunctivitis--physicians in recent years have begun to use antibiotic ointments or eyedrops, namely, tetracycline or erythromycin, for neonatal ophthalmic prophylaxis. Unfortunately, reports indicate that these antibiotics are not always effective in preventing gonococcal or chlamydial conjunctivitis. These failures have prompted some hospitals serving populations at high risk of gonorrheal infections to resume using silver nitrate prophylaxis. The rationale is that chlamydial conjunctivitis rarely causes blindness in newborns, whereas gonorrhea can cause blindness within twenty-four hours.
It has also been established that neonates have large populations of anaerobic bacteria on their eyes. These bacteria may be the cause of some cases of neonatal conjunctivitis of supposed unknown origin some cultures are for bacteria are not routinely taken. Therefore, an ideal antimicrobial prophylactic agent should also have anti-anaerobic bacterial action.
As an added complication, new venereal diseases seem to be appearing with increasing frequency. As the neonate travels through the birth canal the infant can be exposed to the veneral disease infecting the mother. Any one of these diseases might cause neonatal ophthalmic complications if left untreated. Diseases caused by viruses such as herpes simplex or acquired immunodeficiency syndrome (AIDS), and fungal infections such as those caused by Candida, are not affected by silver nitrate or antibiotics. In the case of AIDS, about 50 percent of infants of mothers who are immunopositive for HIV, (the AIDS virus) are born infected. Since the eye is known to be a portal of entry of organisms into the body, the prompt use of an ophthalmic prophylactic agent effective against HIV may prevent infection that may occur from exposure to maternal blood or secretions during birth. Therefore, any proposed new neonatal ophthalmic prophylactic drug must have a wide range of antimicrobial activity.
It would be highly advantageous to have a chemical prophylactic agent that is relatively nonirritating and that has a broad antimicrobial spectrum, preferably including aerobic and anaerobic bacteria, richettsia, viruses, and fungi. Povidone-iodine is known to have activity against these microoganisms including HIV.
One known ophthalmic use for povidone-iodine is in preparing the eye for surgery. However, a presurgical preparation needs to have substantially different properties than a neonatal antimicrobial prophylatic preparation. For example, different bacteria are found in the eyes of newborns, than in the eyes of older children and adults. Because of their recent passage through the birth canal, newborns have ophthalmic bacterial flora more closely resembling an adult female's genital bacterial flora. In addition, the eye of a newborn may be more sensitive or delicate and may require different concentrations of povidone-iodine than that suitable for a preoperative preparation for an adult.